Furnace intake size

[Oldspicesocal]

The furnace intake should be as big as the filter right? Thanks in advance

 

[Breplum]

Mfrs instructions/data show what size min. opening is needed for each model size and it is relative to blower size and much more.
Always minimum is cutout size, on some units two cutouts are required. You can't just look at a furnace and know.

 

[Sponsor]

 

[Oldspicesocal]

Mfrs instructions/data show what size min. opening is needed for each model size and it is relative to blower size and much more.
Always minimum is cutout size, on some units two cutouts are required. You can't just look at a furnace and know.

Thanks for the response.

 

[Fitter30]

Looks small. Size of hole and does it have ac (tonage) if not btu input of furnace?